Project Summary This proposal uses cutting-edge materials science and nanotechnology approaches to improve the safety and effectiveness of cancer immunotherapy. Once cancer metastasizes, surgical removal is no longer an option and medical interventions rarely succeed to cure or even control the disease. Fortunately, therapies that deploy the immune system to fight cancer have led to dramatic cures in previously untreatable metastatic cancers. Patient response to immunotherapy is highly variable, however. This is partly due to insufficient control over delivery of immunotherapy, which is typically limited to systemic infusions that globally activate the immune system. This poor control overstimulates the most accessible parts of the immune system, producing grave toxicity, but inadequately stimulates less accessible anticancer immune cells. We propose to leverage an injectable hydrogel platform we recently developed to precisely orchestrate local and controlled release of multiple immunotherapy drugs, thereby providing an essential tool to engineer effective cancer immune responses. Immune cells evolved to respond to highly specific spatiotemporal cues, such as cascading events, chemical gradients, and sustained exposure to molecular ?danger? signals. Since immune cells process all this information to determine whether to continue battling or to stand down, it is essential to deliver the correct cues to the immune system in the right way. Our approach will control both the timing and localization of cues to improve efforts to study the immune system and deploy it therapeutically. Our preliminary studies show the feasibility of this approach: hydrogel delivery of combination immunotherapy (TRP2 peptide, IL2 cytokine, anti-CD28 antibody, and poly(I:C) TLR3 agonist) dramatically improved survival in the poorly immunogenic B16F10 model of melanoma, whereas standard bolus injections failed. Therefore, we hypothesize that precisely controlled and local delivery of cancer immunotherapy will yield profound benefits in safety and efficacy. This work uses advanced materials science approaches to develop a drug delivery platform that maximizes therapeutic effects while minimizing immune-related toxicities. Our approach will provide a translational path forward for combination therapies that are otherwise too toxic for clinical implementation. We will systematically study the immune response to critical immunomodulatory agents in the context of local, sustained release. In Aim 1, we will interrogate the impact and potential synergy of antibody combinations that specifically stimulate the immune system?s adaptive and innate arms. In Aim 2, we will characterize the rewiring of the immune system due to prolonged exposure to diverse toll-like receptor (TLR) agonists. In Aim 3, we will further refine our hydrogel platform to deliver precise schedules of drug that better mimic cues seen in endogenous immune responses. All studies will be conducted in murine models of cancer to simultaneously assess anticancer efficacy and safety of our immunotherapeutic gels.